STEAP1 is much more strongly expressed in tumor cells than in normal tissues and its expression is associated with the malignant phenotype of several types of cancers, including prostate cancer, head and neck squamous cell carcinoma, Ewing family tumors, breast cancer, and melanoma [3,9,10,11,12,13]. Here, STEAP1 is linked to Ewing sarcoma/peripheral primitive neuroectodermal tumor.